SALT LAKE CITY (AP) — Enrollment in health care plans on the federal government’s website spiked in Utah in December as thousands who previously were stuck in the pipeline got signed up, government figures released Monday show.

About 18,600 people had signed up for plans in Utah by Dec. 28. That’s more than 10 times the total at the end of November.

The spike occurred across the country as people scrambled to beat enrollment deadlines. Nearly 2.2 million had signed up nationwide through late December, more than six times the November total.

The online federal marketplace that went live in October was plagued by glitches, leading to a slow start for enrollment.

In addition to those who already have chosen their plans, thousands more in Utah are in the process of getting enrolled. The new federal figures show nearly 32,000 people have completed their applications but have yet to choose a plan. Nationally, 4.3 million people are in the pipeline.

Utah’s enrollees are significantly younger than those in most of the rest of the country, according to the administration’s breakdowns on those who signed up for government-subsidized private insurance through the federal and state markets.

Twenty-nine percent of Utah residents enrolled are young adults ages 18 to 34. That’s a higher percentage than all but two states: Massachusetts and the District of Columbia, which have far fewer total enrollees. Nationally, 24 percent of enrollees come from that age group.

Like the rest of the country, adults ages 55 to 64 were the most heavily represented age group in Utah. But, this age group accounts for just 25 percent of total enrollees in Utah, a lower percentage than every state except Kentucky, Massachusetts and the District of Columbia.

Utah also is among the states with the highest percentage of people 25 and under with new health care plans, alongside North Dakota, Arizona and Idaho.

The numbers aren’t surprising considering Utah has the country’s lowest median age. University of Utah research economist Pam Perlich said Utah’s youthful population is due to two factors.

The first is the prevalence of members of The Church of Jesus Christ of Latter-day Saints, which puts a high value on having children. The youthful population was reinforced by a wave of immigrants who came to Utah starting in the mid-1990s until the recession of 2007, Perlich said. Many of them came in their 20s, when people often have children, and many were Hispanics, who tend to have larger families.

At least one Utah health organization made an effort to court young people for health care plans. In December, Take Care Utah launched a social media campaign with ads it posted on Twitter and Facebook. They included ads that showed people snowboarding, rock climbing and biking.

The snowboard ad said, “The only thing riskier than catching big air in Utah? Not having health insurance.” The goal was to encourage a group known as the “young invincibles” to sign up.

The breakdown of men and woman in Utah mirrors the national trend. In Utah, more women than men have signed up: 53 percent to 47 percent. Nationally, 54 percent of those who signed up were women, a slightly higher proportion of women than in the population.

Like the rest of the country, about four out of five who signed up in Utah received financial help with their premiums.

The most popular coverage option in Utah was a so-called silver plan, which covers about 70 percent of expected medical costs. Slightly more than half of the people signed up have chosen that plan, compared with about three out of five people nationally.

The gold plan, which most closely compares to the typical employer plan, has been much more popular than around the country. Nearly three out of 10 people have signed up for this plan in Utah, compared with only about one out of 10 nationally.